U.S. patent application number 14/806032 was filed with the patent office on 2016-09-29 for carrier set for electrostatic charge image developer, electrostatic charge image developer set, and process cartridge.
This patent application is currently assigned to FUJI XEROX CO., LTD.. The applicant listed for this patent is FUJI XEROX CO., LTD.. Invention is credited to Moegi IGUCHI, Akihiro IIZUKA, Soutaro KAKEHI, Sakon TAKAHASHI.
Application Number | 20160282753 14/806032 |
Document ID | / |
Family ID | 56975190 |
Filed Date | 2016-09-29 |
United States Patent
Application |
20160282753 |
Kind Code |
A1 |
KAKEHI; Soutaro ; et
al. |
September 29, 2016 |
CARRIER SET FOR ELECTROSTATIC CHARGE IMAGE DEVELOPER, ELECTROSTATIC
CHARGE IMAGE DEVELOPER SET, AND PROCESS CARTRIDGE
Abstract
A carrier set for electrostatic charge image developer,
includes: a first carrier that satisfies Expression (1); 160
mJ.ltoreq.x.ltoreq.200 mJ, and a second carrier that satisfies
Expression (2); 210 mJ.ltoreq.y.ltoreq.250 mJ, wherein x is a total
energy amount, which is measured by a powder rheometer, of a
developer which is prepared by mixing the first carrier and a toner
for measurement such that a weight ratio of the toner is 8% by
weight based on the developer, and y is a total energy amount,
which is measured by the powder rheometer, of a developer which is
prepared by mixing the second carrier and the toner for measurement
such that a weight ratio of the toner is 8% by weight based on the
developer.
Inventors: |
KAKEHI; Soutaro; (Kanagawa,
JP) ; IGUCHI; Moegi; (Kanagawa, JP) ;
TAKAHASHI; Sakon; (Kanagawa, JP) ; IIZUKA;
Akihiro; (Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJI XEROX CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
FUJI XEROX CO., LTD.
Tokyo
JP
|
Family ID: |
56975190 |
Appl. No.: |
14/806032 |
Filed: |
July 22, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03G 9/10 20130101; G03G
15/0808 20130101; G03G 15/09 20130101; G03G 2215/0607 20130101;
G03G 2215/0609 20130101 |
International
Class: |
G03G 9/00 20060101
G03G009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2015 |
JP |
2015-061679 |
Claims
1. A carrier set for electrostatic charge image developer,
comprising: a first carrier that satisfies Expression (1); 160
mJ.ltoreq.x.ltoreq.200 mJ, and a second carrier that satisfies
Expression (2); 210 mJ.ltoreq.y.ltoreq.250 mJ, wherein x is a total
energy amount, which is measured by a powder rheometer, of a
developer which is prepared by mixing the first carrier and a toner
for measurement such that a weight ratio of the toner is 8% by
weight based on the developer, and y is a total energy amount,
which is measured by the powder rheometer, of a developer which is
prepared by mixing the second carrier and the toner for measurement
such that a weight ratio of the toner is 8% by weight based on the
developer.
2. The carrier set according to claim 1 wherein a value of x is
within a range of 165 mJ to 195 mJ.
3. The carrier set according to claim 1, wherein a value of y is
within a range of 215 mJ to 240 mJ.
4. The carrier set according to claim 1 wherein the second carrier
contains a core containing magnetic particle, and a coating layer
that contains a coating resin and oil treated resin particles, and
the oil treated resin particles are exposed on a surface of the
coating layer.
5. The carrier set according to claim 4, wherein the oil treated
resin particles are silicone particles.
6. The carrier set according to claim 1, wherein the second carrier
is a replenishment carrier to be added to the developer in which
the first carrier is included.
7. The carrier set according to claim 4, wherein the oil is
silicone oil.
8. An electrostatic charge image developer set, comprising: an
electrostatic charge image developer that contains a toner and a
first carrier that satisfies Expression (1); 160
mJ.ltoreq.x.ltoreq.200 mJ, a replenishment toner, and a second
carrier that satisfies Expression (2); 210 mJ.ltoreq.y.ltoreq.250
mJ, as a replenishment carrier, wherein x is a total energy amount,
which is measured by a powder rheometer, of a developer which is
prepared by mixing the first carrier and a toner for measurement
such that a weight ratio of the toner is 8% by weight based on the
developer, and y is a total energy amount, which is measured by the
powder rheometer, of a developer which is prepared by mixing the
second carrier and the toner for measurement such that a weight
ratio of the toner is 8% by weight based on the developer.
9. The electrostatic charge image developer set according to claim
8, wherein the replenishment carrier contains a core containing
magnetic particle and a coating layer that contains a coating resin
and oil treated resin particles and coats the core, and wherein the
oil treated resin particles are exposed on a surface of the coating
layer.
10. The electrostatic charge image developer set according to claim
9, wherein the resin particles are silicone particles.
11. The electrostatic charge image developer set according to claim
9, wherein the oil is silicone oil.
12. A process cartridge that is detachable from an image forming
apparatus, the process cartridge comprising: a developing unit that
accommodates an electrostatic charge image developer including a
toner and a carrier, and develops the electrostatic charge image
formed on a surface of an image holding member as a toner image by
using the electrostatic charge image developer; and a replenishing
unit that accommodates a replenishment toner and a replenishment
carrier, and replenishes the electrostatic charge image developer
in the developing unit with the replenishment toner and the
replenishment carrier, wherein the electrostatic charge image
developer is an electrostatic charge image developer that includes
a first carrier that satisfies Expression (1); 160
mJ.ltoreq.x.ltoreq.200 mJ, and the replenishment carrier contains a
second carrier which satisfies Expression (2); 210
mJ.ltoreq.y.ltoreq.250 mJ, wherein x is a total energy amount,
which is measured by a powder rheometer, of a developer which is
prepared by mixing the first carrier and a toner for measurement
such that a weight ratio of the toner is 8% by weight based on the
developer, and y is a total energy amount, which is measured by the
powder rheometer, of a developer which is prepared by mixing the
second carrier and the toner for measurement such that a weight
ratio of the toner is 8% by weight based on the developer.
13. The process cartridge according to claim 12, wherein the
replenishment carrier contains a core containing magnetic particle,
and a coating layer that contains a coating resin and oil treated
resin particles and coats the core, and wherein the oil treated
resin particles are exposed on a surface of the coating layer.
14. The process cartridge according to claim 13, wherein the resin
particles are silicone particles.
15. The process cartridge according to claim 13, wherein the oil is
silicone oil.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2015-061679 filed Mar.
24, 2015.
BACKGROUND
Technical Field
[0002] The present invention relates to a carrier set for
electrostatic charge image developer, an electrostatic charge image
developer set, and a process cartridge.
SUMMARY
[0003] According to an aspect of the invention, there is provided a
carrier set for electrostatic charge image developer,
including:
[0004] a first carrier that satisfies Expression (1); 160
mJ.ltoreq.x.ltoreq.200 mJ, and
[0005] a second carrier that satisfies Expression (2); 210
mJ.ltoreq.y.ltoreq.250 mJ,
[0006] wherein x is a total energy amount, which is measured by a
powder rheometer, of a developer which is prepared by mixing the
first carrier and a toner for measurement such that a weight ratio
of the toner is 8% by weight based on the developer, and y is a
total energy amount, which is measured by the powder rheometer, of
a developer which is prepared by mixing the second carrier and the
toner for measurement such that a weight ratio of the toner is 8%
by weight based on the developer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Exemplary embodiments of the present invention will be
described in detail based on the following figures, wherein:
[0008] FIG. 1 is a schematic configuration view illustrating an
example of an image forming apparatus according to the exemplary
embodiment;
[0009] FIGS. 2A and 2B are views illustrating a measurement method
of a total energy amount by a powder rheometer;
[0010] FIG. 3 is a view illustrating a relationship between a
vertical load and an energy gradient, which is obtained by the
powder rheometer; and
[0011] FIG. 4 is a schematic view illustrating a shape of a rotary
blade which is used in the powder rheometer.
DETAILED DESCRIPTION
[0012] Hereinafter, an exemplary embodiment of the present
invention will be described. The description and Examples are
examples of the present invention, and a scope of the present
invention is not limited thereto.
[0013] In the specification, (meth)acryl means acryl or methacryl,
(meth)acrylic acid means acrylic acid or methacrylic acid, and
(meth)acrylo means acrylo or methacrylo.
[0014] Carrier Set
[0015] A carrier set for electrostatic charge image developer
(simply referred to as a "carrier set" in some cases) according to
the exemplary embodiment includes a first carrier which satisfies
the following Expression (1) and a second carrier which satisfies
the following Expression (2).
160 mJ.ltoreq.x.ltoreq.200 mJ Expression (1)
210 mJ.ltoreq.y.ltoreq.250 mJ Expression (2)
x in Expression (1) is a total energy amount, which is measured by
a powder rheometer, of a developer which is prepared by mixing the
first carrier and a toner for measurement such that toner weight
ratio is 8% by weight.
[0016] y in Expression (2) is a total energy amount, which is
measured by the powder rheometer, of a developer which is prepared
by mixing the second carrier and the toner for measurement such
that toner weight ratio is 8% by weight.
[0017] In the exemplary embodiment, the measurement of the total
energy amount by the powder rheometer is performed under the
conditions that a speed at a tip end of a rotary blade is 100
mm/sec, an approach angle of the rotary blade is -4.degree. C., and
a ventilation flow rate is 0 ml/min.
[0018] A toner for measurement which is mixed with the first
carrier and the second carrier for measuring the total energy
amount is a toner which is obtained by mixing with 100 parts f
toner particles having a volume average particle diameter of 6.5
.mu.m, a volume average particle diameter distribution index of
1.2, and a shape factor SF1 of 120 to 125, 1.2 parts of hydrophobic
titania, and 1.8 parts of hydrophobic silica.
[0019] The total energy amount of the developer which is measured
by the powder rheometer shows fluidity of the developer. As the
total energy amount increases, fluidity of the developer decreases,
and as the total energy amount decreases, fluidity of the developer
increases.
[0020] A measurement method of the total energy amount and a toner
which is used for measuring the total energy amount according to
the exemplary embodiment will be described later in more
detail.
[0021] According to the carrier set of the exemplary embodiment,
formation of an auger mark (density unevenness having a shape of a
stripe which is formed on an image by defective agitating of the
developer in a developing device) which is caused when image
forming is repeated over a long period of time is prevented. The
mechanism of action is not always apparent, but the following is
assumed.
[0022] In the related art, a two-component developer which is
charged by mixing and agitating the toner and the carrier with each
other is known. The developing device which uses the two-component
developer has a developer accommodation chamber provided with an
agitating unit, makes the toner charged by agitating the
two-component developer inside the developer accommodation chamber,
and uses the charged toner in developing an electrostatic charge
image. Since the toner is consumed as the image forming is
repeated, the two-component developer in the developer
accommodation chamber is controlled such that the toner weight
ratio is in a determined range, for example, by a replenishing unit
which replenishes the developer accommodation chamber with the
toner having an amount corresponding to a density of the image to
be formed.
[0023] In addition, as a developing method which is employed in the
developing device, a so-called trickle developing method which
replenishes the developer accommodation chamber with the toner and
the carrier, and discharges the developer (hereinafter, there is a
case where the developer is referred to as a "deteriorated
developer") including a large amount of deteriorated carrier, is
known.
[0024] However, when an amount of the developer which is
accommodated in the developer accommodation chamber of the
developing device increases or decreases, an image defect which is
called an auger mark is formed on the image. In the developing
device in which the trickle developing method is employed, for
example, the following phenomenon may be generated.
[0025] In general, a supplying force or an agitating force of the
developer decreases as the size of the developing device decreases.
When the size of the developing device is reduced, a developer
which has a relatively high fluidity is employed in the developing
device. However, when the fluidity of the developer which is
accommodated in the developer accommodation chamber is high,
discharging of the deteriorated developer is accelerated, and in
some cases, the amount of the developer in the developer
accommodation chamber tends to decrease. In particular, in the case
where the density of the image which is repeatedly formed is low, a
replenishment amount of the toner is controlled to is further
decreased, a difference between the replenishment amount of the
toner and the carrier and a discharge amount of the deteriorated
developer increases, and the amount of the developer in the
developer accommodation chamber is likely to have a tendency of
decreasing.
[0026] On the contrary, when the developer having a low fluidity
which does not correspond to the supplying force or the agitating
force of the developing device is employed, the discharging of the
deteriorated developer is prevented, and in some cases, the amount
of the developer in the developer accommodation chamber tends to
increase. In particular, in the case where the density of the image
which is repeatedly formed is high, the replenishment amount of the
toner is controlled to be increased, a difference in a reverse
direction increases, and the amount of the developer in the
developer accommodation chamber is likely to have a tendency of
increasing.
[0027] In any case, when the image forming is repeated, an increase
and decrease in the amount of the developer which is accommodated
in the developer accommodation chamber exceeds an allowable range,
and as a result, an auger mark is formed on the image.
[0028] In contrast, in the exemplary embodiment, a carrier set
which is combined with the first carrier that satisfies the
Expression (1) and the second carrier that satisfies the Expression
(2) is provided, and by this carrier set, formation of an auger
mark on the image is prevented.
[0029] The first carrier which satisfies the Expression (1) is a
carrier which is intended to be accommodated in the developer
accommodation chamber of the developing device at the beginning of
the use of the developing device, and is a carrier which is
intended to configure the two-component developer and have higher
fluidity than that of the second carrier. In addition, the second
carrier which satisfies the Expression (2) is a carrier which is
intended to be used as a replenishment carrier to be replenished to
the developer accommodation chamber of the developing device.
[0030] The carrier set of the exemplary embodiment prevents
accumulation of a difference between the replenishment amount of
the toner and the carrier and the discharge amount of the
deteriorated developer, and prevents the formation of an auger mark
which is caused when the image forming is repeated over a long
period of time by substituting the carrier which configures the
two-component developer accommodated in the developer accommodation
chamber of the developing device from the first carrier to the
second carrier, and by decreasing the fluidity of the two-component
developer (however, by decreasing the fluidity only to an extent
that transporting properties of the developer are not spoiled) as
the image forming is repeated.
[0031] The first carrier in the exemplary embodiment is a carrier
which satisfies the above-described Expression (1): 160
mJ.ltoreq.x.ltoreq.200 mJ.
[0032] In the developer which is configured of a carrier in which x
is less than 160 mJ, the fluidity is too high, and even when the
carrier in the developer is substituted with the second carrier,
the amount of the developer of the developer accommodation chamber
tends to decrease when the image forming is repeated, and as a
result, an auger mark is formed. From this point of view, x is 160
mJ or greater, preferably 165 mJ or greater, and more preferably
170 mJ or greater.
[0033] In the developer which is configured of a carrier in which x
exceeds 200 mJ, the fluidity is too low, the fluidity further
decreases when the carrier in the developer is substituted with the
second carrier, the amount of the developer of the developer
accommodation chamber tends to increase when the image forming is
repeated, and as a result, an auger mark is formed. From this point
of view, x is 200 mJ or less, preferably 195 mJ or less, and more
preferably 190 mJ or less.
[0034] The second carrier in the exemplary embodiment is a carrier
which satisfies the above-described Expression (2): 210
mJ.ltoreq.y.ltoreq.250 mJ.
[0035] Even when the first carrier in the developer is substituted
with the carrier in which y is less than 210 mJ, the fluidity of
the developer cannot be sufficiently decreased, and the amount of
the developer of the developer accommodation chamber tends to
decrease when the image forming is repeated, and as a result, an
auger mark is formed. From this point of view, y is 210 mJ or
greater, preferably 215 mJ or greater, and more preferably 220 mJ
or greater.
[0036] When the first carrier in the developer is substituted with
the carrier in which y exceeds 250 mJ, the fluidity of the
developer decreases too much, the amount of the developer of the
developer accommodation chamber tends to increase when the image
forming is repeated, and as a result, an auger mark is formed. From
this point of view, y is 250 mJ or less, preferably 245 mJ or less,
and more preferably 240 mJ of less.
[0037] In the increase and decrease in the total amount of the
developer which is accommodated in the developer accommodation
chamber, a (after/before) weight ratio after and before forming
30,000 images having a toner applied amount of 4.2 g/m.sup.2 and an
area of 0.06 m.sup.2 is preferably from 0.6 to 1.4, more preferably
from 0.7 to 1.3, and still more preferably from 0.8 to 1.2
[0038] Hereinafter, a measurement method of the total energy amount
and the toner which is used for measuring the total energy amount
will be described.
[0039] Measurement Method of Total Energy Amount by Powder
Rheometer
[0040] The powder rheometer is a fluidity measurement device which
measures a rotating torque and a vertical load which are obtained
as the rotary blade rotates in a spiral shape in filled particles
at the same time, and directly acquires the fluidity. By measuring
both the rotating torque and the vertical load, the fluidity which
includes characteristics of the powder itself and the influence of
the external environment is detected. In addition, since the
measurement is performed after setting a state of being filled with
the particles in a determined range, data which has excellent
reproducibility may be obtained.
[0041] FT4 manufactured by Freeman Technology is used as the powder
rheometer and measurement is performed. In addition, in order to
eliminate an influence of temperature and humidity before
measurement, a developer which is kept for 8 hours or more under an
environment in which the temperature is 25.degree. C. and the
humidity is 25% RH is used.
[0042] First, a split container having an inner diameter of 25 mm
(a container which has a cylinder having a height of 22 mm on a
container having a height of 61 mm and a volume of 25 mL, and may
be separated into upper and lower parts) is filled with a developer
of which an amount exceeds 61 mm in height.
[0043] After filing the container with the developer, an operation
of performing homogenization of a sample by agitating the filled
developer is performed. Hereinafter, this operation is called
"conditioning".
[0044] In conditioning, the sample is homogenized by agitating the
rotary blade in a rotating direction without receiving resistance
from the toner so as not to give stress to the filled developer,
and thereby removing the air and a partial stress. A specific
condition for conditioning is that the inside of the container is
stirred from 70 mm to 2 mm in height from a bottom surface, at
4.degree. in an approach angle, and at 40 mm/sec of speed of the
tip end of the rotary blade.
[0045] At this time, since the propeller type rotary blade rotates
and moves downward at the same time, the tip end thereof draws a
spiral, and an angle of a path of the spiral which is drawn by the
propeller tip end at this time is called the approach angle.
[0046] After repeating the conditioning operation 4 times, an upper
end portion of the container of the split container is moved, and
at a position which is 61 mm in height, the developer in a vessel
is leveled, and a toner which fills up the container having a
volume of 25 mL is obtained. The conditioning operation is
performed because it is essential to obtain the powder having a
volume in a determined range for stably acquiring the total energy
amount.
[0047] After performing the conditioning operation 1 time, the
rotating torque and the vertical load are measured when rotating is
performed at 100 mm/sec of speed of the tip end of the rotary blade
while moving from 55 mm to 2 mm in height from the bottom surface
in the container at -4.degree. C. in an approach angle. The
rotating direction of a propeller at this time is a direction
reverse (clockwise when viewed from above) to a direction of the
conditioning.
[0048] A relationship between the vertical load or the rotating
torque with respect to a height H from the bottom surface is
illustrated in FIG. 2A or 2B. The energy gradient (mJ/mm) with
respect to the height H which is acquired from the rotating torque
and the vertical load is illustrated in FIG. 3. An area (a shaded
part in FIG. 3) which is obtained by integrating the energy
gradient of FIG. 3 is the total energy amount (mJ). The total
energy amount is acquired by integrating a section from 2 mm to 55
mm in height from the bottom surface.
[0049] In addition, an average value which is obtained by
performing a cycle of conditioning and energy measurement operation
5 times in order to reduce the influence of an error is set as the
total energy amount (mJ).
[0050] The rotary blade is a two-blade propeller type having a
diameter of .phi.23.5 mm which is illustrated in FIG. 4 and
manufactured by Freeman Technology.
[0051] In addition, when measuring the rotating torque and the
vertical load of the rotary blade, in the exemplary embodiment,
measuring is performed by setting the ventilation flow rate from
the bottom portion of the container to 0 ml/min. In addition, a
flow state of the ventilation flow rate is controlled in FT4
manufactured by Freeman Technology.
[0052] Toner Used for Measuring Total Energy Amount
[0053] In the exemplary embodiment, the total energy amount of the
developer which is prepared by mixing the carrier (the first
carrier and the second carrier) and the toner with each other is
measured. The toner which is used for measuring the total energy
amount is a toner which is prepared by mixing toner particles, with
hydrophobic titania and hydrophobic silica as external additives at
the weight ratio of 100:3. The weight ratio of hydrophobic titania
and hydrophobic silica is 1.2:1.8.
[0054] The toner particles, hydrophobic titania, and hydrophobic
silica used have the following physical properties,
respectively.
[0055] Toner Particles
[0056] Volume average particle diameter: 6.5 .mu.m
[0057] Volume average particle diameter distribution index: 1.2
[0058] Shape factor SF1: 120 to 125
[0059] Hydrophobic titania
[0060] Volume average particle diameter: 0.02 m (for example,
JMT2000 manufactured by Fuji Titanium Industry Co., Ltd.)
[0061] Hydrophobic silica
[0062] Volume average particle diameter: 0.04 .mu.m (for example,
RY50 manufactured by Nippon Aerosil Co., Ltd.)
[0063] The volume average particle diameter, the volume average
particle diameter distribution index, and the shape factor SF1 of
the toner particles are synonymous with a volume average particle
diameter (D50v), a volume average particle diameter distribution
index (GSDv), and a shape factor SF1 which will be described later,
respectively, and the measurement methods thereof are the same.
[0064] As the toner particles which configure the toner for
measuring the total energy amount, toner particles which configure
a known toner which is practically used in the image forming
apparatus may be employed, and toner particles which are prepared
with materials and preparing methods which will be described later
may be employed. As a binder resin of the toner particles, at least
one selected from a styrene acrylic resin and a polyester resin is
preferable. It is preferable that the toner particles contain a
coloring agent and a release agent.
[0065] The external additive (hydrophobic titania and hydrophobic
silica) is externally added to the toner particles by mixing the
materials for 3 minutes at a circumferential speed of 33 m/s using
a HENSCHEL mixer.
[0066] Mixing of the toner for measuring the total energy amount
and the carrier is performed by mixing 8 parts by weight of the
toner and 92 parts by weight of the carrier for 20 minutes at 20
rotations per minute using a V blender.
[0067] Hereinafter, materials, preparing methods, and physical
properties of the first carrier and the second carrier will be
described in detail.
[0068] Second Carrier
[0069] First, the second carrier will be described.
[0070] The second carrier is not particularly limited, as long as
it is a carrier which satisfies the above-described Expression (2),
and a known carrier may be employed as a carrier for the
two-component developer.
[0071] From the viewpoint of satisfying the above-described
Expression (2), it is preferable to employ a magnetic carrier of
the following (a) as the second carrier.
[0072] (a) A magnetic carrier which includes a core containing
magnetic particle, and a coating layer which contains a coating
resin and oil treated resin particles, and coats the core.
[0073] Furthermore, in the magnetic carrier of the (a), it is
preferable that the oil treated resin particles are exposed on a
surface of the coating layer. In this case, at least a part of all
of the particles may be exposed, or a part of individual particles
may be exposed.
[0074] Hereinafter, the magnetic carrier of the (a) will be
described.
[0075] Core Containing Magnetic Particle
[0076] Examples of the core containing the magnetic particles
(hereinafter, simply referred to as a "core" in some cases) include
a core which is formed of particle-shaped magnetic particle; a core
in which the magnetic particles are dispersed in the resin; and a
core in which porous magnetic particle are impregnated with the
resin.
[0077] Examples of the magnetic particle include a magnetic metal
(e.g., iron, nickel, and cobalt), and a magnetic oxide (e.g.,
ferrite and magnetite).
[0078] Examples of the resin which configures the core include
polyethylene, polypropylene, polystyrene, polyvinyl acetate,
polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl
ether, polyvinyl ketone, a vinyl chloride-vinyl acetate copolymer,
a styrene-acrylic acid copolymer, a straight silicone resin
configured to have an organosiloxane bond or a modified article
thereof, a fluorine resin, polyester, polycarbonate, a phenol
resin, or an epoxy resin. These resins may be used alone or in
combination of two or more kinds thereof.
[0079] The resin which configures the core may contain an additive,
such as conductive particles. Examples of the conductive particles
include particles of metal (e.g., gold, silver, and copper), carbon
black, titanium oxide, zinc oxide, tin oxide, barium sulfate,
aluminum borate, and potassium titanate.
[0080] As the core, particle-shaped magnetic particle is
preferable. In this case, the volume average particle diameter of
the magnetic particles which constitute the core is, for example,
preferably from 20 .mu.m to 50 .mu.m. As the magnetic particle
which constitutes the core, ferrite, magnetite or the like is
preferable.
[0081] The volume average particle diameter of the core is, for
example, preferably from 20 .mu.m to 50 .mu.m.
[0082] Coating Layer Examples of the coating resin which configures
the coating layer include polyethylene, polypropylene, polystyrene,
polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl
chloride, polyvinyl ether, polyvinyl ketone, a vinyl chloride-vinyl
acetate copolymer, a styrene-acrylic acid copolymer, a straight
silicone resin configured to have an organosiloxane bond or a
modified article thereof, a fluorine resin, polyester,
polycarbonate, a phenol resin, or an epoxy resin. These resins may
be used alone or in combination of two or more kinds thereof. As
the coating resin, a homopolymer or a copolymer of cyclohexyl
methacrylate is preferable.
[0083] Oil treated Resin Particles
[0084] The coating layer includes resin particles which are oil
treated (hereinafter, referred to as "oil treated resin particles
in some cases).
[0085] Examples of the resin particles which configure the oil
treated resin particles include particles which are formed of a
resin or an elastomer (e.g., silicone, polystyrene, polymethyl
methacrylate, polyethyl methacrylate, a methyl methacrylate-styrene
copolymer, and styrene-butadiene rubber).
[0086] Examples of oil which is used in oil treating of the resin
particles include dimethylsilicone oil, methylphenyl silicone oil,
silicone oil containing an amino group, fluorine-modified silicone
oil, epoxy-modified silicone oil, and mercapto-modified silicone
oil.
[0087] The oil treating of the resin particles may be performed by
a method of dispersing the resin particles in an oil which is
dissolved in alcohol and distilling alcohol by an evaporator to dry
the resultant. An amount of oil which is used in the treating is
from 5 parts by weight to 40 parts by weight, and preferably from
10 parts by weight to 30 parts by weight with respect to 100 parts
by weight of the resin particles.
[0088] As the oil treated resin particles, oil treated silicone
particles are preferable.
[0089] The silicone particles are polysiloxane particles. A
molecular structure of silicone may be linear, branched, or may
have a mixture of the linear and branched structures. Examples of
an organic group which is bonded to a silicon atom include an alkyl
group (e.g., a methyl group, an ethyl group, and a propyl group),
an aryl group (e.g., a phenyl group and a tolyl group), and a
halogenated alkyl group (e.g., a chloromethyl group).
[0090] The silicone particles may be silicone resin particles or
silicone rubber particles, and more specifically, examples thereof
include a crosslinked body of dimethyl polysiloxane, and
polysilsesquioxane and a derivative thereof, which are in a
particle shape. Examples of silicone particles which are available
on the market include X-24 and X-22 manufactured by Shin-Etsu
Chemical Co., Ltd.
[0091] A volume average particle diameter of the oil treated resin
particles is, for example, preferably from 0.1 .mu.m to 10
.mu.m.
[0092] From the viewpoint of satisfying the above-described
Expression (2), a content of the oil treated resin particles is
preferably from 0.05% by weight to 0.2% by weight, and more
preferably from 0.075% by weight to 0.175% by weight, and still
more preferably from 0.1% by weight to 0.15% by weight of the
entire carrier.
[0093] From the viewpoint of satisfying the above-described
Expression (2), it is preferable that at least a part of all of the
oil treated resin particles is exposed on the surface of the
coating layer. In addition, from the viewpoint of satisfying the
above-described Expression (2), a coverage (%) of the surface of
the carrier by the oil treated resin particles is preferably from
0.1% to 10%, more preferably from 0.25% to 5%, and still more
preferably from 0.5% to 1%.
[0094] A state where the oil treated resin particles are exposed on
the surface of the coating layer, and the coverage of the surface
of the carrier by the oil treated resin particles may be confirmed
by X-ray photoelectron spectroscopy (XPS).
[0095] The coating layer may contain the resin particles which are
not oil treated. Examples of the resin particles include particles
of, for example, silicone resin, polystyrene, polymethyl
methacrylate, and melamine resin. The volume average particle
diameter of the resin particles is, for example, preferably from
0.1 .mu.m to 10 .mu.m.
[0096] When the coating layer contains the resin particles which
are not oil treated, the content of the resin particles is
preferably from 0.05% by weight to 0.2% by weight, more preferably
from 0.075% by weight to 0.175% by weight, and still more
preferably from 0.1% by weight to 0.15% by weight of the entire
carrier.
[0097] The coating layer may contain the additive, such as
conductive particles. Examples of the conductive particles include
particles of a metal (e.g., gold, silver, and copper), and carbon
black, titanium oxide, zinc oxide, tin oxide, barium sulfate,
aluminum borate, and potassium titanate.
[0098] Examples of a method of forming the coating layer on the
surface of the core include a method which uses a coating layer
forming solution in which the coating resin and various additives
are dissolved in a solvent.
[0099] Specific examples of the method include a dipping method of
dipping the core in the coating layer forming solution, a spray
method of spraying the coating layer forming solution onto the
surface of the core, a fluid bed method of spraying the coating
layer forming solution in a state where the core floats by fluid
air, and a kneader-coater method of mixing the core and the coating
layer forming solution in the kneader-coater and then, removing the
solvent.
[0100] The solvent which configures the coating layer forming
solution is not particularly limited, and may be selected by
considering the type or excellency in coating of the coating resin
used or coating suitability.
[0101] Examples of a method of making the oil treated resin
particles be contained in the coating layer include a method of
forming the coating layer on the surface of the core by using the
coating layer forming solution to which the oil treated resin
particles are added. Other than this, examples also include a
method of making the oil treated resin particles be adhered and
thus contained in the coating layer by mixing and stirring the
carrier and the oil treated resin particles after making the
carrier which has the coating layer formed of the coating resin on
the surface of the core.
[0102] An average thickness of the coating layer is, for example,
preferably from 0.1 .mu.m to 1 .mu.m.
[0103] The coverage of the surface of the core by the coating layer
is preferably 80% or greater, more preferably 90% or greater, and
may be 100%. The coverage of the surface of the core by the coating
layer is acquired by the X-ray photoelectron spectroscopy
(XPS).
[0104] From the viewpoint of satisfying the above-described
Expression (2), as the second carrier, a magnetic carrier of the
following (d) is also preferable.
[0105] (d) A magnetic carrier which is prepared by performing oil
treating on the surfaces of the magnetic carriers of the
above-described (a), or (b) or (c) which will be described
later.
[0106] Examples of oil which is used in the oil treating of the
magnetic carrier for obtaining the above-described (d) include
dimethylsilicone oil, methylphenyl silicone oil, silicone oil
containing an amino group, fluorine-modified silicone oil,
epoxy-modified silicone oil, and mercapto-modified silicone oil.
The oil treating of the magnetic carrier may be performed by the
method of distilling and drying alcohol by using an evaporator
after dispersing the magnetic carrier in the oil which is dissolved
in alcohol. An amount of oil which is used in the treating is from
0.1 parts by weight to 10 parts by weight, and preferably from 0.5
parts by weight to 5 parts by weight with respect to 100 parts by
weight of the magnetic carrier
[0107] The volume average particle diameter of the second carrier
is, for example, preferably from 20 .mu.m to 50 .mu.m.
[0108] First Carrier
[0109] Next, the first carrier will be described.
[0110] The first carrier is not particularly limited as long as the
carrier satisfies the above-described Expression (1), and a carrier
known as a carrier for the two-component developer may be
employed.
[0111] From the viewpoint of satisfying the above-described
Expression (1), as the first carrier, a magnetic carrier of the
following (b) and (c) is preferable.
[0112] (b) A magnetic carrier which includes the core containing
the magnetic particles; and the coating layer which contains the
coating resin and coats the core.
[0113] In the magnetic carrier of the (b), the coating layer does
not contain the resin particles (resin particles which are oil
treated, and resin particles which are not oil treated).
[0114] (c) A magnetic carrier which includes the core containing
the magnetic particle; and the coating layer which contains the
coating resin and the resin particles, and coats the core. The
resin particles are resin particles which are not oil treated.
[0115] In the magnetic carrier of the (c), the resin particles may
be exposed on the surface of the coating layer. In the magnetic
carrier of the (c), the coating layer does not contain the oil
treated resin particles.
[0116] Hereinafter, the magnetic carrier of the (b) and (c) will be
described.
[0117] The core and the coating resin that contains the magnetic
particles in the (b) and (c) are configured similarly to the core
and the coating resin which contains the magnetic particles in the
second carrier, and a preferable aspect is also similar.
[0118] The resin particles in the (c) are the resin particles which
are not oil treated, and examples thereof include particles of
silicone, polystyrene, polymethyl methacrylate, and melamine resin.
The volume average particle diameter of the resin particles which
are not oil treated is, for example, preferably from 0.1 .mu.m to
10 .mu.m.
[0119] When the coating layer contains the resin particles which
are not oil treated, a content of the resin particles is preferably
from 0.05% by weight to 0.2% by weight, more preferably from 0.075%
by weight to 0.175% by weight, and still more preferably from 0.1%
by weight to 0.15% by weight of the entire carrier.
[0120] The coating layer may contain the additive, such as
conductive particles. Examples of the conductive particles include
particles of a metal (e.g., gold, silver, and copper), and carbon
black, titanium oxide, zinc oxide, tin oxide, barium sulfate,
aluminum borate, and potassium titanate.
[0121] Examples of the method of forming the coating layer on the
surface of the core include a method which uses a coating layer
forming solution in which the coating resin, the resin particles,
and various additives as necessary are dissolved in a solvent.
[0122] Specific examples of the method include the dipping method
of dipping the core in the coating layer forming solution, the
spray method of spraying the coating layer forming solution onto
the surface of the core, the fluidized bed method of spraying the
coating layer forming solution in a state where the core floats by
flowing air, and the kneader-coater method of mixing the core and
the coating layer forming solution in the kneader-coater and then,
removing the solvent.
[0123] The solvent for forming the coating layer forming solution
is not particularly limited, and may be selected by considering the
type of the coating resin used or coating suitability.
[0124] An average thickness of the coating layer is, for example,
preferably from 0.1 .mu.m to 1 .mu.m.
[0125] The coverage of the surface of the core by the coating layer
is preferably 80% or greater, more preferably 90% or greater, and
may be 100%.
[0126] A volume average particle diameter of the first carrier is,
for example, preferably from 20 .mu.m to 50 .mu.m.
[0127] Electrostatic Charge Image Developer Set
[0128] An electrostatic charge image developer set (referred to as
a "developer set" in some cases) according to the exemplary
embodiment includes the developer which has the toner and the first
carrier that satisfies the above-described Expression (1), a
replenishment toner, and the second carrier which satisfies the
above-described Expression (2) as a replenishment carrier. The
replenishment toner may have the same configuration as the toner
which configures the developer together with the first carrier, or
may have a different configuration, but the toner which has the
same configuration is preferable.
[0129] In the electrostatic charge image developer which configures
the developer set according to the exemplary embodiment, a mixing
ratio (weight ratio) between the toner and the first carrier is
from 3:100 to 12:100, and preferably from 5:100 to 9:100.
[0130] Hereinafter, materials, a preparing method, and physical
properties of the toner which configures the developer set
according to the exemplary embodiment will be described in
detail.
[0131] Toner
[0132] The toner contains toner particles, and further, may contain
an external additive. In other words, the exemplary embodiment may
use the toner particles may be used as the toner as they are, and
those prepared by externally adding an external additive to the
toner particles.
[0133] Toner Particles
[0134] The toner particles are configured to contain, for example,
a binder resin, and as necessary, a coloring agent, a release
agent, and other additives.
[0135] Binder Resin
[0136] Examples of the binder resin include a vinyl resin which is
formed of a homopolymer of a monomer, such as styrenes (e.g.,
styrene, parachlorostyrene, and .alpha.-methylstyrene),
(meth)acrylic esters (e.g., methyl acrylate, ethyl acrylate,
n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl
acrylate, methyl methacrylate, ethyl methacrylate, n-propyl
methacrylate, lauryl methacrylate, and 2-ethylhexyl methacrylate),
ethylenic unsaturated nitriles (e.g., acrylonitrile and
methacrylonitrile), vinyl ethers (e.g., vinylmethylether and vinyl
isobutyl ether), vinyl ketones (e.g., vinyl methyl ketone, vinyl
ethyl ketone, and vinyl isopropenyl ketone), olefins (e.g.,
ethylene, propylene, and butadiene), and a copolymer of two or more
of the monomers.
[0137] Examples of the binder resin include non-vinyl resin (e.g.,
an epoxy resin, a polyester resin, a polyurethane resin, a
polyamide resin, a cellulose resin, a polyether resin, and a
modified rosin), a mixture of these and the above-described vinyl
resin, and a graft polymer which is obtained by polymerizing the
vinyl monomer under the conditions that these resins are present
together.
[0138] These binder resins may be used alone or in combination of
two or more kinds thereof.
[0139] As the binder resin, the polyester resin is appropriate.
Example of the polyester resin includes a polycondensate of
polyvalent carboxylic acid and polyol.
[0140] Examples of the polyvalent carboxylic acid include aliphatic
dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid,
fumaric acid, citraconic acid, itaconic acid, glutaconic acid,
succinic acid, alkenyl succinic acids, adipic acid, and sebacic
acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic
acid), aromatic dicarboxylic acids (e.g., terephthalic acid,
isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid),
anhydrides thereof, or lower alkyl esters (having, for example,
from 1 to 5 carbon atoms) thereof. Among these, for example,
aromatic dicarboxylic acids are preferably used as the polyvalent
carboxylic acid.
[0141] As the polyvalent carboxylic acid, a tri- or higher-valent
carboxylic acid employing a crosslinked structure or a branched
structure may be used in combination with a dicarboxylic acid.
Examples of the tri- or higher-valent carboxylic acid include
trimellitic acid, pyromellitic acid, anhydrides thereof, or lower
alkyl esters (having, for example, from 1 to 5 carbon atoms)
thereof.
[0142] The polyvalent carboxylic acids may be used alone or in
combination of two or more kinds thereof.
[0143] Examples of the polyol include aliphatic diol (e.g.,
ethylene glycol, diethylene glycol, triethylene glycol, propylene
glycol, butanediol, hexanediol, or neopentyl glycol), alicyclic
diol (e.g., cyclohexanediol, cyclohexanedimethanol, or hydrogenated
bisphenol A), or aromatic diol (e.g., ethylene oxide adduct of
bisphenol A, or propylene oxide adduct of bisphenol A). Among
these, as the polyol, for example, the aromatic diol and the
alicyclic diol are preferable, and the aromatic diol is more
preferable.
[0144] As the polyol, a tri- or higher-valent polyol employing a
crosslinked structure or a branched structure may be used in
combination with diol. Examples of the tri- or higher-valent polyol
include glycerin, trimethylolpropane, or pentaerythritol.
[0145] The polyol may be used alone or in combination of two or
more kinds thereof.
[0146] A glass transition temperature (Tg) of the polyester resin
is preferably from 50.degree. C. to 80.degree. C., and more
preferably from 50.degree. C. to 65.degree. C.
[0147] The glass transition temperature is acquired by a DSC curve
which is obtained by differential scanning calorimetry (DSC). More
specifically, the glass transition temperature is acquired by an
"extrapolated starting temperature of glass transition" described
in an acquiring method of the glass transition temperature of a JIS
K7121-1987 "transition temperature measurement method of
plastic".
[0148] A weight average molecular weight (Mw) of the polyester
resin is preferably from 5,000 to 1,000,000, and more preferably
from 7,000 to 500,000. A number average molecular weight (Mn) of
the polyester resin is preferably from 2,000 to 100,000. A
molecular weight distribution Mw/Mn of the polyester resin is
preferably from 1.5 to 100, and more preferably from 2 to 60.
[0149] The weight average molecular weight and the number average
molecular weight are measured by gel permeation chromatography
(GPC). The measurement of the molecular weight by the GPC is
performed in a THF solvent by using HLC-8120, which is a GPC
manufactured by Tosoh Corporation as a measurement apparatus and
TSKGEL SuperHM-M(15 cm), which is a column manufactured by Tosoh
Corporation. The weight average molecular weight and the number
average molecular weight are calculated by using a molecular weight
calibration curve which is obtained by a monodispersed polystyrene
reference sample from the measurement result.
[0150] The polyester resin may be obtained by a known preparation
method. Specifically, for example, the polyester resin may be
obtained by a method in which a polymerization temperature is set
to be from 180.degree. C. to 230.degree. C., pressure is reduced in
a reaction system as necessary, and a reaction is performed while
removing water or alcohol formed during condensation.
[0151] When a monomer of a raw material is not dissolved or is not
compatible at a reaction temperature, a solvent having a high
boiling point may be added as a solubilizing agent and dissolution
may be performed. In this case, the polycondensation reaction is
performed while distilling the solubilizing agent. When a monomer
having a low compatibility exists in a copolymerization reaction,
it is preferable that the monomer having a low compatibility is
condensed with an acid or alcohol which is planned to be
polycondensed with the monomer in advance, and then polycondensed
with a main component.
[0152] A content of the binder resin, for example, with respect to
the entire toner particle, is preferably from 40% by weight to 95%
by weight, more preferably from 50% by weight to 90% by weight, and
still more preferably from 60% by weight to 85% by weight.
[0153] Coloring Agent
[0154] Examples of the coloring agent include various types of
pigments, such as carbon black, chrome yellow, Hansa yellow,
benzidine yellow, threne yellow, quinoline yellow, pigment yellow,
permanent orange GTR, pyrazolone orange, vulcan orange, Watchung
red, permanent red, brilliant carmine 3B, brilliant carmine 6B,
Dupont oil red, pyrazolone red, lithol red, rhodamine B lake, lake
red C, pigment red, rose Bengal, aniline blue, ultramarine blue,
chalco oil blue, methylene blue chloride, phthalocyanine blue,
pigment blue, phthalocyanine green, or malachite green oxalate; and
various dyes, such as acridine dye, xanthene dye, azo dye,
benzoquinone dye, azine dye, anthraquinone dye, thioindigo dye,
dioxazine dye, thiazine dye, azomethine dye, indigo dye,
phthalocyanine dye, aniline black dye, polymethine dye,
triphenylmethane dye, diphenylmethane dye, or thiazole dye.
[0155] The coloring agent may be used alone or in combination of
two or more kinds thereof.
[0156] As the coloring agent, a surface-treated coloring agent may
be used as necessary, and the coloring agent and a dispersing agent
may be used together. In addition, plural coloring agents may be
used together.
[0157] The content of the coloring agent is preferably from 1% by
weight to 30% by weight, and more preferably from 3% to 15% by
weight with respect to the entirety of the toner particles.
[0158] Release Agent
[0159] Examples of the release agent include hydrocarbon waxes;
natural waxes such as carnauba wax, rice wax, and candelilla wax;
synthetic or mineral/petroleum waxes such as montan wax; and ester
waxes such as fatty acid esters and montanic acid esters. The
release agent is not limited thereto.
[0160] A melting temperature of the release agent is preferably
from 50.degree. C. to 110.degree. C., and more preferably from
60.degree. C. to 100.degree. C.
[0161] The melting temperature of the release agent is acquired
from a DSC curve which is obtained by differential scanning
calorimetry (DSC), by a "melting peak temperature" described in an
acquiring method of the melting temperature of a JIS K7121-1987
"Testing methods for transition temperatures of plastics".
[0162] The content of the release agent is, for example, preferably
from 1% by weight to 20% by weight and more preferably from 5% by
weight to 15% by weight with respect to the entirety of the toner
particles.
[0163] Other Additives
[0164] Examples of other additives include known additives such as
a magnetic material, a charge-controlling agent, and an inorganic
powder. The toner particles contain these additives as internal
additives.
[0165] Characteristics of Toner Particles
[0166] The toner particles may be toner particles having a single
layer structure, or may be toner particles having a so-called core
shell structure which is configured of a core (core particles) and
a coating layer (shell layer) which coats the core.
[0167] Here, for example, the toner particles having the core shell
structure may preferably be configured of a core which includes a
binder resin and other additives, such as a coloring agent and a
release agent as necessary, and a coating layer which includes the
binder resin.
[0168] The volume average particle diameter (D50v) of the toner
particle is preferably from 2 .mu.m to 10 .mu.m, and more
preferably from 4 .mu.m to 8 .mu.m.
[0169] Various average particle diameters and various particle
diameter distribution indexes of the toner particles are measured
by using a COULTER MULTISIZER-II (manufactured by Beckman coulter)
and an ISOTON-II (manufactured by Beckman coulter) as an
electrolyte.
[0170] During the measurement, 0.5 mg to 50 mg of the measurement
sample is added to 2 ml of aqueous solution having 5% by weight of
surfactant (sodium alkylbenzene sulfonate is preferable) as the
dispersing agent. This is added to 100 ml to 150 ml of the
electrolyte.
[0171] Dispersion processing is performed for 1 minute by an
ultrasonic homogenizer with respect to the electrolyte which
suspends the sample. By the Coulter MULTISIZER-II, the particle
diameter distribution of the particle having 2 .mu.m to 60 .mu.m of
particle diameter is measured by using an aperture which is 100
.mu.m in an aperture diameter. The number of particles sampled is
50,000.
[0172] By drawing cumulative distribution of each of the volume and
the number from a small diameter side with respect to a particle
diameter range (channel) divided based on the measured particle
diameter distribution, a particle diameter which has 16% of
cumulation is defined as a volume particle diameter D16v and a
number particle diameter D16p, a particle diameter which has 50% of
cumulation is defined as a volume average particle diameter D50v
and a number average particle diameter D50p, and a particle
diameter which has 84% of cumulation is defined as a volume
particle diameter D84v and a number particle diameter D84p.
[0173] By using these, a volume average particle diameter
distribution index (GSDv) is calculated by (D84v/D16v).sup.1/2, and
a number average particle diameter distribution index (GSDp) is
calculated by (D84p/D16p).sup.1/2.
[0174] The shape factor SF1 of the toner particles is preferably
from 110 to 150, and more preferably from 120 to 140.
[0175] The shape factor SF1 is obtained through the following
equation.
SF1=(ML.sup.2/A).times.(.pi./4).times.100 Equation:
[0176] In the above-described equation, ML represents an absolute
maximum length of the toner particle, and A represents a projected
area of the toner particle.
[0177] Specifically, the shape factor SF1 is numerically converted
mainly by analyzing a microscopic image or a scanning electron
microscopic (SEM) image by the use of an image analyzer, and is
calculated as follows. In other words, an optical microscopic image
of particles scattered on a surface of a glass slide is put to an
image analyzer LUZEX through a video camera to obtain maximum
lengths and projected areas of 100 particles, values of SF1 are
calculated through the above-described equation, and an average
value thereof is obtained.
[0178] External Additives Examples of the external additive include
inorganic particles. Examples of the inorganic particles include
SiO.sub.2, TiO.sub.2, Al.sub.2O.sub.3, CuO, ZnO, SnO.sub.2,
CeO.sub.2, Fe.sub.2O.sub.3, MgO, BaO, CaO, K.sub.2O, Na.sub.2O,
ZrO.sub.2, CaO.SiO.sub.2, K.sub.2O.(TiO.sub.2).sub.n,
Al.sub.2O.sub.3.2SiO.sub.2, CaCO.sub.3, MgCO.sub.3, BaSO.sub.4, and
MgSO.sub.4.
[0179] Surfaces of the inorganic particles as an external additive
are preferably subjected to a treatment with a hydrophobizing
agent. The hydrophobizing treatment is performed by, for example,
dipping the inorganic particles in a hydrophobizing agent. The
hydrophobizing agent is not particularly limited and examples
thereof include a silane coupling agent, silicone oil, a titanate
coupling agent, and an aluminum coupling agent. These may be used
alone or in combination of two or more kinds thereof.
[0180] Generally, the amount of the hydrophobizing agent is, for
example, from 1 part by weight to 10 parts by weight with respect
to 100 parts by weight of the inorganic particles.
[0181] Examples of the external additive also include resin
particles (resin particles, such as polystyrene, PMMA, and melamine
resin particles) and a cleaning activator (e.g., metal salt of a
higher fatty acid represented by zinc stearate, and fluorine
polymer particles).
[0182] The amount of the external additives to be externally added
is, for example, preferably from 0.01% by weight to 5% by weight,
and more preferably from 0.01% by weight to 2.0% by weight with
respect to the toner particles.
[0183] Method of Preparing Toner
[0184] Next, the method of preparing the toner according to the
exemplary embodiment will be described.
[0185] The toner according to the exemplary embodiment is obtained
by externally adding the external additives to the toner particles
after preparing the toner particles.
[0186] The toner particles may be prepared by any of a dry
preparing method (e.g., a kneading and pulverizing method) and a
wet preparing method (e.g., an aggregation and coalescence method,
a suspending and polymerizing method, and a dissolving and
suspending method). The preparing method of the toner particles is
not particularly limited to these methods, and a known preparing
method is employed.
[0187] Among these, the toner particle may be obtained by the
aggregation and coalescence method.
[0188] Specifically, for example, when preparing the toner
particles by the aggregation and coalescence method, the toner
particles are prepared via a process (resin particle dispersion
preparing process) of preparing a resin particle dispersion in
which the resin particles which become the binder resin are
dispersed; a process (aggregated particle forming process) of
forming aggregated particles by aggregating the resin particles
(other particles as necessary) in the resin particle dispersion (in
the dispersion after mixing other particle dispersions therein as
necessary); and a process (coalescing process) of forming the toner
particles by heating an aggregated particle dispersion in which the
aggregated particles are dispersed, and by coalescing the
aggregated particles.
[0189] Hereinafter, each process will be described in detail.
[0190] In the description below, a method of obtaining the toner
particles which contain the coloring agent and the release agent
will be described, but the coloring agent and the release agent are
used as necessary. It goes without saying that additives other than
the coloring agent and the release agent may be used.
[0191] Resin Particle Dispersion Preparing Process
[0192] The coloring agent particle dispersion in which coloring
agent particles are dispersed and a release agent dispersion in
which release agent particles are dispersed, are prepared in
addition to the resin particle dispersion in which the resin
particles which become the binder resin are dispersed.
[0193] The resin particle dispersion is prepared, for example, by
dispersing the resin particles in a dispersion medium by a
surfactant.
[0194] Examples of the dispersion medium used for the resin
particle dispersion include aqueous mediums.
[0195] Examples of the aqueous mediums include water such as
distilled water and ion exchange water, and alcohol. These may be
used alone or in combination of two or more kinds thereof.
[0196] Examples of the surfactant include anionic surfactants such
as sulfate ester salt, sulfonate, phosphate, and soap anionic
surfactants; cationic surfactants such as amine salt and quaternary
ammonium salt cationic surfactants; and nonionic surfactants such
as polyethylene glycol, alkylphenol ethylene oxide adduct, and
polyol nonionic surfactants. Among these, anionic surfactants and
cationic surfactants are particularly used. Nonionic surfactants
may be used in combination with anionic surfactants or cationic
surfactants.
[0197] The surfactants may be used alone or in combination of two
or more kinds thereof.
[0198] In the resin particle dispersion, examples of a dispersing
method of the resin particles in the dispersion medium include a
general dispersing method which uses a rotation shearing type
homogenizer or a ball mill, a sand mill, or a DYNO mill, which each
has a media. In addition, the resin particles may be dispersed in
the resin particle dispersion by using a phase inversion
emulsification method according to the type of the resin
particles.
[0199] The phase inversion emulsification method is a method of
performing resin inversion (so-called phase inversion) from W/O to
O/W, making non-continuous phase, and dispersing the resin in the
aqueous medium in a particle shape, by dissolving the resin to be
dispersed into a hydrophobic organic solvent in which the resin is
soluble, and putting aqueous medium (W phase) after performing
neutralization by adding a base into an organic continuous phase (O
phase).
[0200] The volume average particle diameter of the resin particles
which are dispersed in the resin particle dispersion is preferably
from 0.01 .mu.m to 1 .mu.m, and more preferably from 0.08 .mu.m to
0.8 .mu.m, and still more preferably from 0.1 .mu.m to 0.6 .mu.m,
for example.
[0201] In the volume average particle diameter of the resin
particles, the particle diameter distribution which is obtained by
measurement of a laser diffraction type particle diameter
distribution measurement apparatus (for example, LA-700
manufactured by Horiba, Ltd.) is used, the cumulative distribution
regarding the volume from the small particle diameter side with
respect to the divided particle diameter range (channel) is drawn,
and 50% of the volume with respect to the entirety of the particles
is set as the volume average particle diameter D50v. The volume
average particle diameters of the particles in other dispersions
are measured in a similar manner.
[0202] The content of the resin particle which is included in the
resin particle dispersion is preferably from 5% by weight to 50% by
weight, and more preferably from 10% by weight to 40% by
weight.
[0203] Similarly to the resin particle dispersion, the coloring
agent dispersion and the release agent dispersion are also
prepared. In other words, the volume average particle diameter, the
dispersion medium, and the dispersing method of the particles, and
the content of the particle in the resin particle dispersion, are
also similar in the coloring agent particles which are dispersed in
the coloring agent dispersion and the release agent particles which
are dispersed in the release agent dispersion.
[0204] Aggregated Particles Forming Process
[0205] Next, the coloring agent particle dispersion and the release
agent particle dispersion are mixed with resin particle
dispersion.
[0206] In addition, in the mixed dispersion, the resin particles,
the coloring agent particles, and the release agent particles are
heteroaggregated to form the aggregated particles which have a
diameter which is close to a target diameter of the toner
particles, and include the resin particles, the coloring agent
particles, and the release agent particles.
[0207] Specifically, for example, the aggregated particles are
formed by adding an aggregating agent into the mixed dispersion,
adjusting pH of the mixed dispersion to be acidic (e.g., from pH 2
to pH 5), adding a dispersion stabilizer as necessary, and then,
performing heating to the temperature close to the glass transition
temperature of the resin particles (specifically, for example, from
a temperature 30.degree. C. lower than the glass transition
temperature of the resin particles to a temperature 10.degree. C.
lower than the glass transition temperature), and aggregating the
particles which are dispersed in the mixed dispersion.
[0208] In the aggregated particle forming process, for example,
heating may be performed after adding the aggregating agent at a
room temperature (e.g., 25.degree. C.) while stirring the mixed
dispersion by the rotation shearing type homogenizer, adjusting pH
of the mixed dispersion to be acidic (e.g., from pH 2 to pH 5), and
adding the dispersion stabilizer as necessary.
[0209] Examples of the aggregating agent include a surfactant
having a polarity reversed to that of the surfactant which is
contained the mixed dispersion, inorganic metal salt, and a di- or
higher-valent metal complex. When the metal complex is used as the
aggregating agent, an amount of use of the surfactant is reduced,
and charging characteristics are improved.
[0210] Together with the aggregating agent, an additive which forms
a complex or a similar bond to a bond for the formation of a
complex, with the metal ion of the aggregating agent, may be used
as necessary. As the additive, a chelating agent may be
appropriately used.
[0211] Examples of the inorganic metal salt include metal salt
(e.g., calcium chloride, calcium nitrate, barium chloride,
magnesium chloride, zinc chloride, aluminum chloride, and aluminum
sulfate), and an inorganic metal salt polymer (e.g., polyaluminum
chloride, polyaluminium hydroxide, and calcium polysulfide).
[0212] As the chelating agent, a water-soluble chelating agent may
be used. Examples of the chelating agent include an oxycarboxylic
acid (e.g., a tartaric acid, a citric acid, and a gluconic acid),
and an aminocarboxylic acid (e.g., an iminodiacetic acid (IDA), a
nitrilotriacetic acid (NTA), and an ethylenediaminetetraacetic acid
(EDTA)).
[0213] An addition amount of the chelating agent is preferably from
0.01 parts by weight to 5.0 parts by weight, and more preferably
0.1 parts by weight to less than 3.0 parts by weight with respect
to 100 parts by weight of the resin particles.
[0214] Coalescing Process
[0215] Next, the toner particles are formed by coalescing the
aggregated particles by heating the aggregated particle dispersion
in which the aggregated particles are dispersed, for example, at a
temperature not lower than a glass transition temperature of the
resin particles (e.g., equal to or greater than a temperature which
is higher than the glass transition temperature of the resin
particles by 10.degree. C. to 30.degree. C.).
[0216] In the above-described process, the toner particles are
obtained.
[0217] After obtaining the aggregated particle dispersion in which
the aggregated particles are dispersed, the toner particles may be
prepared via a process of forming second aggregated particles by
further mixing the aggregated particle dispersion and the resin
particle dispersion in which the resin particles are dispersed, and
aggregating the mixture so that the resin particles are further
adhered to the surface of the aggregated particles, and a process
of forming the toner particles having the core shell structure by
heating the second aggregated particle dispersion in which the
second aggregated particles are dispersed, and coalescing the
second aggregated particles.
[0218] Here, after finishing the coalescing process, a known
washing process, a solid-liquid separation process, and a drying
process are performed on the toner particles which are formed in
the solvent, and the toner particles which are in a dried state are
obtained.
[0219] From the viewpoint of charge properties, preferably, the
washing process may be sufficiently performed by displacement
washing by the ion exchange water. In addition, the solid-liquid
separation process is not particularly limited, but from the
viewpoint of productivity, suction filtration, pressure filtration,
or the like, may be performed preferably. In addition, the drying
process is also not particularly limited, but from the viewpoint of
productivity, freeze drying, flash jet drying, drying, vibration
type fluidized drying, or the like, may be performed.
[0220] In addition, the toner according to the exemplary embodiment
is prepared, for example, by adding and mixing the external
additive into the obtained toner particles in a dried state. Mixing
may be performed, for example, by a V blender, a HENSCHEL mixer, or
a LbDIGE mixer. Furthermore, as necessary, by using a vibration
classifier or a wind classifier, coarse particles of the toner may
be removed.
[0221] Image Forming Apparatus/Image Forming Method
[0222] The image forming apparatus according to the exemplary
embodiment is provided with an image holding member; a charging
unit that charges a surface of the image holding member, an
electrostatic charge image forming unit that forms an electrostatic
charge image on the charged surface of the image holding member; a
developing unit which accommodates an electrostatic charge image
developer containing a toner and a carrier, and develops the
electrostatic charge image formed on the surface of the image
holding member as a toner image by using the electrostatic charge
image developer; a transfer unit which transfers the toner image
formed on the surface of the image holding member onto a surface of
a recording medium; a fixing unit that fixes the toner image
transferred onto the surface of the recording medium; and a
replenishing unit which accommodates a replenishment toner and a
replenishment carrier, and replenishes the electrostatic charge
image developer in the developing unit with the replenishment toner
and the replenishment carrier.
[0223] In the image forming apparatus according to the exemplary
embodiment, the electrostatic charge image developer set according
to the exemplary embodiment is employed, the developing unit
accommodates the electrostatic charge image developer for
constituting the electrostatic charge image developer set according
to the exemplary embodiment at the beginning of the use of the
developing unit, and the replenishing unit accommodates the
replenishment toner and the second carrier for constituting the
electrostatic charge image developer set according to the exemplary
embodiment.
[0224] In the image forming apparatus according to the exemplary
embodiment, an image forming method (image forming method according
to the exemplary embodiment) including a charging process of
charging a surface of an image holding member; an electrostatic
charge image forming process of forming an electrostatic charge
image on the charged surface of the image holding member; a
developing process of developing the electrostatic charge image
formed on the surface of the image holding member as a toner image
by using the developing unit which accommodates the electrostatic
charge image developer containing a toner and a carrier; a transfer
process of transferring the toner image formed on the surface of
the image holding member onto a surface of a recording medium; a
fixing process of fixing the toner image transferred onto the
surface of the recording medium; and a replenishing process of
replenishing the electrostatic charge image developer in the
developing unit with a replenishment toner and a replenishment
carrier, is performed.
[0225] In the image forming method according to the exemplary
embodiment, the electrostatic charge image developer set according
to the exemplary embodiment is employed, the developing unit
accommodates the electrostatic charge image developer for
constituting the electrostatic charge image developer set according
to the exemplary embodiment at the beginning of the use of the
developing unit, and the replenishing process replenishes the
electrostatic charge image developer in the developing unit with
the replenishment toner and the second carrier for constituting the
electrostatic charge image developer set according to the exemplary
embodiment.
[0226] As the image forming apparatus according to the exemplary
embodiment, a known image forming apparatus is applied, such as a
direct transfer-type apparatus which directly transfers the toner
image formed on the surface of the image holding member to the
surface of the recording medium; an intermediate transfer-type
apparatus which primarily transfers the toner image formed on the
surface of the image holding member onto a surface of an
intermediate transfer member, and secondarily transfers the toner
image transferred onto the surface of the intermediate transfer
member onto the surface of the recording medium; an apparatus which
includes a cleaning unit that cleans the surface of the image
holding member, after transferring the toner image and before
charging; and an apparatus which includes an erasing unit that
performs erasing by irradiating the surface of the image holding
member with erasing light, after transferring the toner image and
before charging.
[0227] In a case where the image forming apparatus according to the
exemplary embodiment is an intermediate transfer-type apparatus, a
transfer unit includes, for example, an intermediate transfer
member having a surface onto which a toner image is to be
transferred, a primary transfer unit that primarily transfers a
toner image formed on the surface of the image holding member onto
the surface of the intermediate transfer member, and a secondary
transfer unit that secondarily transfers the toner image
transferred onto the surface of the intermediate transfer member
onto the surface of the recording medium.
[0228] In the image forming apparatus according to the exemplary
embodiment, for example, a part including the developing unit and
the replenishing unit may have a cartridge structure (process
cartridge) which is detachable from the image forming apparatus. As
the process cartridge, for example, a process cartridge which is
provided with the developing unit that accommodates the
electrostatic charge image developer for constituting the
electrostatic charge image developer set according to the exemplary
embodiment, and the replenishing unit that accommodates the
replenishment toner and the second carrier for constituting the
electrostatic charge image developer set according to the exemplary
embodiment is preferably used.
[0229] Hereinafter, the developing unit and the replenishing unit
according to the exemplary embodiment will be described in more
detail.
[0230] The developing unit employs a trickle developing type which
discharges the developer (deteriorated developer) containing a
large amount of deteriorated carrier while replenishing the toner
and the carrier.
[0231] The developing unit is provided with, for example, the
developer accommodation chamber which accommodates the developer;
an stirring unit (e.g., screw) which is provided in the developer
accommodation chamber, and agitates and transports the developer; a
developing member (e.g., roll-shaped member) which holds the toner
and transports the toner to the surface of the image holding
member; a toner replenishing port which receives the replenishment
toner; a carrier replenishing port which receives the replenishment
carrier; and a developer discharge port which discharges the
deteriorated developer. It is preferable that the toner
replenishing port, the carrier replenishing port, and the developer
discharge port are respectively provided in the developer
accommodation chamber, and are mechanisms which may be opened and
closed.
[0232] Inside the developer accommodation chamber, the developer is
stirred by the stirring unit, and the toner is charged by friction
between the toner and the carrier. A part of the charged toner is
held by the developing member and transported to the surface of the
image holding member. The developer accommodation chamber is
replenished with the toner and the carrier from the toner
replenishing port and the carrier replenishing port, and meanwhile,
the developer which contains a large amount of carrier deteriorated
by the agitation is slowly discharged from the developer discharge
port.
[0233] The replenishing unit is provided with, for example, a
replenishment toner accommodation chamber which accommodates the
replenishment toner, a replenishment carrier accommodation chamber
which accommodates the replenishment carrier, a toner replenishing
path which links the replenishment toner accommodation chamber and
the developing unit to each other, and a carrier replenishing path
which links the replenishment carrier accommodation chamber and the
developing unit to each other. The replenishment toner
accommodation chamber and the replenishment carrier accommodation
chamber may be a cartridge which may be detachable from the image
forming apparatus.
[0234] In addition, the toner replenishing path and the carrier
replenishing path may be one path being linked to each other in
front of the developing unit, and in this case, one replenishing
port which functions as both the toner replenishing port and the
carrier replenishing port may be provided in the developing
unit.
[0235] In addition, in the replenishing unit, one accommodation
chamber which functions as both the replenishment toner
accommodation chamber and the replenishment carrier accommodation
chamber may be provided, and a developer which is mixed with the
replenishment toner and the second carrier may be accommodated in
the accommodation chamber.
[0236] In the developer which is accommodated in the developer
accommodation chamber of the developing unit, the mixing ratio
(weight ratio) between the toner and the carrier is preferably from
3:100 to 12:100, and more preferably from 5:100 to 9:100. It is
preferable that a developer which satisfies this range is
accommodated in the developer accommodation chamber at the
beginning of the use. In addition, it is preferable that the
developing unit is replenished with the replenishment toner and the
replenishment carrier from the replenishing unit so as to satisfy
this range.
[0237] In the image forming apparatus and the image forming method
according to the exemplary embodiment, it is preferable that the
developer which is accommodated in the developing unit satisfies
the following Expression (3).
0.6.ltoreq.B'/B.ltoreq.1.4 Expression (3)
[0238] B and B' in Expression (3) are total weights of the
developer which is accommodated in the developing unit. The total
weight before forming 30,000 images having a toner applied amount
of 4.2 g/m.sup.2 and an area of 0.06 m.sup.2 is B, and the total
weight after forming images is B'.
[0239] In a case where the image is formed according to the
above-described conditions, when a change in the amount of the
developer which is accommodated in the developing unit is within
the range of Expression (3), formation of an auger mark which is
caused when the image forming is repeated over a long period of
time is prevented.
[0240] Hereinafter, an example of the image forming apparatus
according to the exemplary embodiment will be described, but the
exemplary embodiment is not limited thereto. In the following
description, main parts illustrated in the drawing will be
described, and the description of other parts will be omitted.
[0241] FIG. 1 is a schematic configuration view illustrating the
image forming apparatus according to the exemplary embodiment.
[0242] The image forming apparatus illustrated in FIG. 1 is
provided with first to fourth electrophotographic image forming
units 10Y, 10M, 10C, and 10K (image forming units) which output
images of each colors, such as yellow (Y), magenta (M), cyan (C),
and black (K), based on color-separated image data. These image
forming units (hereinafter, there is a case where the image forming
unit is simply referred to as a "unit") 10Y, 10M, 10C, and 10K are
aligned in parallel to be separated from each other by a preset
distance in a horizontal direction. These units 10Y, 10M, 10C, and
10K may be process cartridges which are detachable from the image
forming apparatus.
[0243] At an upper part of the drawing of each unit 10Y, 10M, 10C,
and 10K, an intermediate transfer belt 20 passes through each unit
and extends as the intermediate transfer member. The intermediate
transfer belt 20 is provided to be wound around a driving roll 22
and a supporting roll 24 which is in contact with an inner surface
of the intermediate transfer belt 20, which are disposed to be
separated from each other from left to right in the drawing, and
travels in a direction toward the fourth unit 10K from the first
unit 10Y. In addition, a force is applied to the supporting roll 24
in a direction away from the driving roll 22 by a spring or the
like, which is not illustrated, and a tension is given to the
intermediate transfer belt 20 which is wound around both the
driving roll 22 and the supporting roll 24. In addition, on the
image holding member side of the intermediate transfer belt 20, an
intermediate transfer member cleaning is provided facing the
driving roll 22.
[0244] The image forming apparatus illustrated in FIG. 1 is
provided with a replenishing device (replenishing unit) which
includes replenishment chambers 8Y, 8M, 8C, and 8K, and
replenishing path (not illustrated). The developing devices
(developing units) 4Y, 4M, 4C, and 4K of each of units 10Y, 10M,
10C, and 10K are respectively connected to the replenishment
chambers 8Y, 8M, 8C, and 8K by the replenishing path. The
replenishment chambers 8Y, 8M, 8C, and 8K are respectively provided
in the attachable and detachable replenishment toner accommodation
chamber (not illustrated) and the attachable and detachable
replenishment carrier accommodation chamber (not illustrated), and
the developing devices 4Y, 4M, 4C, and 4K are replenished with the
toner and the carrier of each color from the replenishment chambers
8Y, 8M, 8C, and 8K.
[0245] Since the first to the fourth units 10Y, 10M, 10C, and 10K
have the same configurations as each other, here, the first unit
10Y which is arranged on an upstream side of a traveling direction
of an intermediate transfer belt and which forms a yellow image,
will be described as a representative example. In addition, by
providing reference numerals with magenta (M), cyan (C), and black
(K) at a similar part to that of the first unit 10Y, instead of
yellow (Y), the description of the second to the fourth units 10M,
10C, and 10K will be omitted.
[0246] The first unit 10Y has a photoreceptor 1Y which operates as
the image holding member. In the periphery of the photoreceptor 1Y,
a charging roll (an example of the charging unit) 2Y which charges
a front surface of the photoreceptor 1Y to a preset potential, an
exposure device (an example of the electrostatic charge image
forming unit) 3 which forms the electrostatic charge image by
exposing the charged surface by using a laser beam 3Y based on a
color-separated image signal, a developing device (an example of
the developing unit) 4Y which supplies the charged toner to the
electrostatic charge image and develops the electrostatic charge
image, a primary transfer roll 5Y (an example of the primary
transfer unit) which transfers the developed toner image onto the
intermediate transfer belt 20, and a photoreceptor cleaning device
(an example of the cleaning unit) 6Y which removes the toner that
remains on the surface of the photoreceptor 1Y after the primary
transfer, are disposed in order.
[0247] The primary transfer roll 5Y is disposed on an inner side of
the intermediate transfer belt 20, and is provided at a position
which faces the photoreceptor 1Y. Each of bias supplies (not
illustrated) which apply a primary transfer bias are connected to
each of primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias supply
varies the transfer bias applied to each of the primary transfer
rolls, by a control of a control portion which is not
illustrated.
[0248] Hereinafter, an operation of forming the yellow image in the
first unit 10Y will be described.
[0249] First, before the operation, a surface of the photoreceptor
1Y is charged to a potential having -600 V to -800 V by using the
charging roll 2Y.
[0250] The photoreceptor 1Y is formed by layering a photosensitive
layer on a substrate having conductivity (for example, a volume
resistivity at 20.degree. C.: 1.times.10.sup.-6 .OMEGA.cm or less).
The photosensitive layer generally has high resistance (resistance
of a general resin), but it has a property that the photosensitive
layer is irradiated with the laser beam 3Y, specific resistance of
a part which is irradiated with the laser beam changes. Here, the
laser beam 3Y is output to the surface of the charged photoreceptor
1Y via the exposure device 3, according to the image data for
yellow which is sent from the control portion that is not
illustrated. The photosensitive layer of the surface of the
photoreceptor 1Y is irradiated with the laser beam 3Y, and
accordingly, the electrostatic charge image having a yellow image
pattern is formed on the surface of the photoreceptor 1Y.
[0251] The electrostatic charge image is an image which is formed
on the surface of the photoreceptor 1Y by charging, and is a
so-called negative latent image which is formed as the specific
resistance of the irradiated part of the photosensitive layer
decreases by the laser beam 3Y, and a charge on the surface of the
photoreceptor 1Y flows, and meanwhile, the charge at a part which
is not irradiated with the laser beam 3Y remains.
[0252] The electrostatic charge image formed on the photoreceptor
1Y is rotated up to a preset development position according to the
traveling of the photoreceptor 1Y. At this development position,
the electrostatic charge image on the photoreceptor 1Y is developed
and visualized as the toner image, by a developing device 4Y.
[0253] In the developing device 4Y, for example, the electrostatic
charge image developer which includes at least the yellow toner and
the carrier is accommodated. The yellow toner is friction-charged
by agitation in the developing device 4Y, and has a charge having
the same polarity (negative polarity) as a band charge on the
photoreceptor 1Y and is held on a developer roll (an example of a
developer holding member).
[0254] As the surface of the photoreceptor 1Y passes through the
developing device 4Y, the yellow toner is electrostatically adhered
to a latent image portion which is erased on the surface of the
photoreceptor 1Y, and the latent image is developed by the yellow
toner. The photoreceptor 1Y in which the yellow toner image is
formed travels continuously at a preset speed, and the toner image
which is developed on the photoreceptor 1Y is transported to a
preset primary transfer position.
[0255] Since the toner is consumed as the image forming is
repeated, the developing device 4Y is replenished with the yellow
toner which is in the replenishment chamber 8Y. In addition, the
developing device 4Y is also replenished with the carrier from the
replenishment chamber 8Y. The developing device 4Y has the
developer discharge port (not illustrated) and gradually discharges
the developer which includes a large amount of deteriorated
carrier.
[0256] When the yellow toner image on the photoreceptor 1Y is
transported to the primary transfer position, a primary transfer
bias is applied to the primary transfer roll 5Y, the electrostatic
force toward the primary transfer roll 5Y from the photoreceptor 1Y
acts on the toner image, and the toner image on the photoreceptor
1Y is transferred onto the intermediate transfer belt 20. The
transfer bias which is applied at this time has a (+) polarity
reverse to (-) polarity of the toner, and for example, is
controlled to be +10 .mu.A by the control portion (not illustrated)
in the first unit 10Y.
[0257] Meanwhile, the toner which remains on the photoreceptor 1Y
is removed and collected by the photoreceptor cleaning device
6Y.
[0258] A first transfer bias which is applied to the first transfer
rolls 5M, 5C, and 5K of the second unit 10M and subsequent units is
also controlled according to the first unit.
[0259] In this manner, the intermediate transfer belt 20 in which
the yellow toner image is transferred by the first unit 10Y is
transported sequentially in order through the second to the fourth
units 10M, 10C, and 10K, and the toner images having each color are
superimposed and multiply transferred.
[0260] The intermediate transfer belt 20 to which the toner images
of four colors are multiply transferred through the first to the
fourth units, reaches a secondary transfer portion which is
configured of the intermediate transfer belt 20, the supporting
roll 24 which is in contact with the inner surface of the
intermediate transfer belt, and a secondary transfer roll (an
example of the secondary transfer unit) 26 which is disposed on an
image holding surface side of the intermediate transfer belt 20.
Meanwhile, a recording paper sheet (an example of the recording
medium) P is supplied at a preset timing to a gap between which the
secondary transfer roll 26 and the intermediate transfer belt 20
which contact with each other, via a supply mechanism, and a
secondary transfer bias is applied to the supporting roll 24. The
transfer bias which is applied at this time has (-) polarity which
is the same polarity as (-) polarity of the toner, the
electrostatic force toward the recording paper sheet P from the
intermediate transfer belt 20 acts on the toner image, and the
toner image on the intermediate transfer belt 20 is transferred
onto the recording paper sheet P. In addition, the secondary
transfer bias at this time is determined according to the
resistance which is detected by a resistance detecting unit (not
illustrated) that detects resistance of the secondary transfer
portion, and is voltage-controlled.
[0261] After this, the recording paper sheet P is sent into a press
contact portion (nipped portion) of a pair of fixing rolls in a
fixing device (an example of the fixing unit) 28, the toner image
is fixed onto the recording paper sheet P, and the fixed image is
formed.
[0262] Examples of the recording paper sheet P to which the toner
image is transferred include a plain paper sheet which is used in
an electrophotographic type copying machine or a printer. In
addition to the recording paper sheet P, examples of the recording
medium also include an OHP sheet or the like.
[0263] In order to further improve the smoothness of the surface of
the image after fixing is performed, it is preferable that the
surface of the recording paper sheet P is also smooth, and for
example, a coated paper sheet which is prepared by coating a
surface of the plain paper sheet with resin or the like, or an art
paper sheet for printing, is preferably used.
[0264] The recording paper sheet P on which the fixing of the color
image is completed is discharged toward a discharge portion, and a
series of the color image forming operations ends.
[0265] Process Cartridge
[0266] A process cartridge according to the exemplary embodiment
will be described.
[0267] The process cartridge according to the exemplary embodiment
includes the developing unit which accommodates the electrostatic
charge image developer containing the toner and the carrier, and
develops the electrostatic charge image formed on the surface of
the image holding member as the toner image by using the
electrostatic charge image developer; and the replenishing unit
which accommodates the replenishment toner and the replenishment
carrier, and replenishes the replenishment toner and the
replenishment carrier to the electrostatic charge image developer
in the developing unit. The process cartridge is attachable to and
detachable from the image forming apparatus.
[0268] In the process cartridge according to the exemplary
embodiment, the electrostatic charge image developer set according
to the exemplary embodiment is employed, the developing unit
accommodates the electrostatic charge image developer which
configures the electrostatic charge image developer set according
to the exemplary embodiment, and the replenishing unit accommodates
the replenishment toner and the second carrier which configures the
electrostatic charge image developer set according to the exemplary
embodiment.
[0269] The process cartridge according to the exemplary embodiment
is not limited to the above-described configuration, and may be
configured to include the developing unit, the replenishing unit,
and at least one selected from other units, such as the image
holding member, the charging unit, the electrostatic charge image
forming unit, or the transfer unit, as necessary.
Example
[0270] Hereinafter, the present invention will be described in more
detail by using Example, but the invention is not limited to the
following Example unless the contents are within the scope of the
invention.
[0271] In the following description, "parts" and "%" are on a
weight basis if there is no particular notice.
[0272] Preparation of Toner
[0273] Preparation of Styrene Acrylic Resin Particle Dispersion
[0274] Styrene: 320 parts
[0275] n-butyl acrylate: 80 parts
[0276] Acrylic acid: 12 parts
[0277] 10-dodecanthiol: 2 parts
[0278] A mixture which is prepared by mixing and dissolving the
above-described materials is emulsified and dispersed is added to
550 parts of ion exchange water to which 6 parts of nonionic
surfactant (NONYPOL 400 manufactured by Sanyo Chemical Co., Ltd.)
and 10 parts of anionic surfactant (NEOGEN SC manufactured by DKS
Co., Ltd.) in a flask, and while mixing the resultant for 10
minutes slowly, 50 parts of ion exchange water to which 4 parts of
ammonium persulfate is added is put thereto. After performing
nitrogen substitution, while stirring the inside of the flask, the
contents are heated in an oil bath up to 70.degree. C., and
emulsion-polymerization is continued for 5 hours. As a result, a
styrene acrylic resin particle dispersion (1) having a volume
average particle diameter (D50v) of 210 nm, a glass transition
temperature (Tg) of 50.degree. C., a weight average molecular
weight (Mw) of 38,000, and a solid content of 30% is obtained.
[0279] Preparation of Release Agent Dispersion
[0280] Paraffin wax (HNP-9 manufactured by Nippon Seiro Co., Ltd.):
50 parts
[0281] Anionic surfactant (NEOGEN SC manufactured by DKS Co.,
Ltd.): 2 parts
[0282] Ion exchange water: 200 parts
[0283] After heating the above-described materials to 120.degree.
C., and sufficiently mixing and dispersing the materials by using a
homogenizer (ULTRA-TURRAX T50 manufactured by IKA), dispersion
processing is performed by a pressure discharge type homogenizer,
and a release agent dispersion (1) having a volume average particle
diameter of 200 nm and a solid content of 20% is obtained.
[0284] Preparation of Coloring Agent Dispersion
[0285] Cyan pigment (C.I. Pigment Blue 15:3 manufactured by
Dainichiseika Color & Chemicals Mfg. Co., Ltd.): 20 parts
[0286] Anionic surfactant (NEOGEN SC manufactured by DKS Co.,
Ltd.): 2 parts
[0287] Ion exchange water: 80 parts
[0288] By mixing the above-described materials, and dispersing the
mixture for 1 hour by using a high pressure impact type dispersing
machine ultimizer (HJP30006 manufactured by Sugino Machine
Limited), a coloring agent dispersion (1) having a volume average
particle diameter of 180 nm and a solid content of 20% is
obtained.
[0289] Preparation of Toner Particles
[0290] Styrene acrylic resin particle dispersion (1): 200 parts
[0291] Release agent dispersion (1): 30 parts
[0292] Coloring agent dispersion (1): 25 parts
[0293] Polyaluminum chloride: 0.4 parts
[0294] Ion exchange water: 100 parts
[0295] After putting the above-described materials into a flask
made of stainless steel, mixing the materials by using the
homogenizer (ULTRA-TURRAX T50 manufactured by IKA), and dispersing
the mixture, the temperature is heated up to 48.degree. C. while
stirring the flask by the oil bath for heating. After keeping the
mixture for 30 minutes at 48.degree. C., here, 70 parts of styrene
acrylic resin particle dispersion (1) is added thereto.
[0296] Then, after adjusting the pH in a system to 8.0 by using
sodium hydroxide aqueous solution having 0.5 mol/L of
concentration, the flask made of stainless steel is tightly closed,
and while continuing stirring by magnetically sealing an stirring
shaft, the temperature is heated up to 90.degree. C., and the
mixture is held for 3 hours. After completing the reaction, cooling
is performed at 2.degree. C./minute of temperature lowering speed,
filtering is performed, and washing by the ion exchange water is
performed. Then, solid-liquid separation is performed by Nutsche
type suction filtration. Further, this is further dispersed again
by using 3 L of ion exchange water at 30.degree. C., stirring is
performed at 300 rpm for 15 minutes, and washing is performed. This
washing operation is repeated 6 times, and when pH of the filtrate
is 7.54 and electric conductivity is 6.5 .mu.S/cm, solid-liquid
separation is performed by using No. 5A filter paper by Nutsche
type suction filtration. Next, vacuum drying is continued for 12
hours, and the toner particles are obtained. The toner particles
have a volume average particle diameter of 6.5 .mu.m, a volume
average particle diameter distribution index of 1.2, and a shape
factor SF1 of 122.
[0297] External Addition of External Additive
[0298] 1.2 parts of hydrophobic titania (JMT2000 manufactured by
Fuji Titanium Industry Co., Ltd.) and 1.8 parts of hydrophobic
silica (RY50 manufactured by Nippon Aerosil Co., Ltd.) are added
into 100 parts of toner particles, and the resultant is mixed by
using a HENSCHEL mixer to obtain an externally added toner.
[0299] Preparation of Carrier A
[0300] Carriers A1 to A4 which are a resin coating type magnetic
carriers and contain silicone particles that are not oil treated in
the coating layer are prepared.
[0301] Carrier A1
[0302] Preparation of Silicone Particles
[0303] 100 parts of methyl vinyl polysiloxane and 10 parts of
methyl hydrogen siloxane are mixed with each other, 30 parts of
calcium carbonate powder (number average particle size: 0.1 .mu.m,
TP-123 manufactured by Okutama Kogyo Co., Ltd.), 1 part of
polyoxyethylene octylphenylether, and 200 parts of water are added
into the mixture, and emulsification is performed for 3 minutes at
6,000 rpm by a mixer. After this, chloroplatinic acid-olefin
complex salt is added in an amount of 0.001 parts as an amount of
platinum, and polymerization-reaction is performed for 10 hours at
80.degree. C. under a nitrogen atmosphere. Then, after putting
hydrochloric acid thereto to decompose calcium carbonate, washing
is performed with water. By wet classification, porous elastomer
particles having target volume particle diameter D16v and volume
particle diameter D50v are collected, vacuum drying is performed
for 12 hours at 100.degree. C., and thus the silicone particles are
obtained.
[0304] Preparation of Magnetic Carrier
[0305] 2,000 parts of ferrite particles (Mn--Mg ferrite, true
specific gravity: 4.7 g/cm.sup.3, volume average particle diameter:
45 .mu.m, saturation magnetization: 60 emu/g, surface roughness:
1.5 .mu.m) are put into a vacuum degassing type kneader having a
volume of 5 L, and further, 380 parts of a resin coating layer
forming solution is put thereto. While stirring, the pressure is
reduced down to -200 mmHg at 60.degree. C. and stirring is
continued for 20 minutes. Then, the temperature is increased and
the pressure is reduced, and stirring is performed for 30 minutes
at 70.degree. C./-720 mHg for drying, thereby obtaining resin
coating particles. Next, classification is performed by using a
sieve having an aperture of 75 .mu.m to obtain a carrier. 0.1 parts
of silicone particles are added to 100 parts of the obtained
carrier, stirring is performed for 15 minutes at 40 rpm by using a
V blender, and thus the carrier A1 is obtained.
[0306] Composition of Resin Coating Layer Forming Solution
[0307] Cyclohexyl methacrylate/dimethylaminoethyl copolymer resin:
3 parts
[0308] Toluene: 20 parts
[0309] Measurement of Total Energy Amount
[0310] 92 parts of the carrier A1 and 8 parts of the externally
added toner are put into a V blender, stirred for 20 minutes, and
mixed with each other. After this, by classifying the mixture by
using a sieve having an aperture of 212 .mu.m, a developer is
prepared.
[0311] After keeping this developer for 17 hours under an
environment in which the temperature is 25.degree. C. and humidity
is 25% RH, the total energy amount is measured according to the
above-described operations and conditions by using a powder
rheometer (FT4 manufactured by Freeman Technology).
[0312] Carrier A2
[0313] Carrier A2 is prepared in the same manner as in the
preparation of the carrier A1, except that the amount of silicone
particles is changed to 0.01 parts.
[0314] Carrier A3
[0315] Carrier A3 is prepared in the same manner as in the
preparation of the carrier A1, except that the silicone particles
are not added.
[0316] Carrier A4
[0317] Carrier A4 is prepared in the same manner as in the
preparation of the carrier A1, except that the volume average
particle diameter of ferrite particles is changed to 35 .mu.m.
[0318] Preparation of Carrier B
[0319] Carriers B1 to B4, which are resin coating type magnetic
carriers and contain oil treated silicone particles in the coating
layer, are prepared.
[0320] Carrier B1
[0321] Preparation of Oil treated Silicone Particles
[0322] 100 parts of methyl vinyl polysiloxane and 10 parts of
methyl hydrogen siloxane are mixed with each other, 30 parts of
calcium carbonate powder (average particle size: 0.1 .mu.m, TP-123
manufactured by Okutama Kogyo Co., Ltd.), 1 part of polyoxyethylene
octylphenylether, and 200 parts of water are added into the
mixture, and emulsification is performed for 3 minutes at 6,000 rpm
by a mixer. After this, chloroplatinic acid olefin complex salt is
added in an amount of 0.001 parts as an amount of platinum, and
polymerization-reaction is performed for 10 hours at 80.degree. C.
under a nitrogen atmosphere. Then, after putting hydrochloric acid
thereto to decompose calcium carbonate, washing is performed with
water. By wet classification, porous elastomer particles having
target volume particle diameter D16v and volume particle diameter
D50v are collected, and vacuum drying is performed for 12 hours at
100.degree. C.
[0323] Then, a solution prepared by dissolving 150 parts of
dimethylsilicone oil into 1,000 parts of ethanol, is stirred and
mixed with 100 parts of porous elastomer particles, ethanol being
the solvent is distilled by using an evaporator and drying is
performed, and thus the oil treated silicone particles are
obtained.
[0324] Preparation of Magnetic Carrier
[0325] 2,000 parts of ferrite particles (Mn--Mg ferrite, true
specific gravity of 4.7 g/cm.sup.3, volume average particle
diameter of 45 .mu.m, saturation magnetization of 60 emu/g, surface
roughness of 1.5 .mu.m) are put into a vacuum degassing type
kneader having a volume of 5 L, and further, 380 parts of the
following resin coating layer forming solution is put thereto.
While stirring this, after reducing the pressure down to -200 mmHg
at 60.degree. C. and mixing this for 20 minutes, resin coating
particles are obtained by increasing the temperature, reducing the
pressure, stirring for 30 minutes at 70.degree. C./-720 mHg, and
drying. Next, classification by using a sieve having an aperture of
75 .mu.m is performed, and the carrier is obtained. 0.12 parts of
oil treated silicone particles are added to 100 parts of the
obtained carrier, stirring is performed for 15 minutes at 40 rpm by
using a V blender, and the carrier B1 is obtained.
[0326] Composition of Resin Coating Layer Forming Solution
[0327] Cyclohexyl methacrylate copolymer resin: 3 parts
[0328] Toluene: 20 parts
[0329] Analysis of Surface of Resin Particles by XPS
[0330] The carrier B1 is fixed to a sample holder of X-ray
photoelectron spectrometer (JPS-9000MX manufactured by JEOL Ltd.,
excitation source Mg--K.alpha.), and inserted into a chamber of the
X-ray photoelectron spectrosmeter. XPS spectrum is measured by
setting a degree of vacuum of the chamber to 1.times.10.sup.-6 Pa
or less and an output to 200 W. A spectrum in the vicinity of 100
eV is measured regarding Si--O, a spectrum in the vicinity of 110
eV is measured regarding Si 2p, a spectrum in the vicinity of 290
eV is measured regarding C 1s, a spectrum in the vicinity of 537 eV
is measured regarding O 1s, a spectrum in the vicinity of 404 eV is
measured regarding N 1s, a spectrum in the vicinity of 644 eV is
measured regarding Mn 2p, a spectrum in the vicinity of 715 eV is
measured regarding Fe 2p, a spectrum in the vicinity of 462 eV is
measured regarding Ti 2p, a spectrum in the vicinity of 138 eV is
measured regarding Sr 3d, a spectrum in the vicinity of 88 eV is
measured regarding Mg 2s, and a spectrum in the vicinity of 694 eV
is measured regarding F 1s. Based on the spectrums of each element,
from a ratio between a spectrum strength of Si--O and a spectrum
strength of other elements, a coverage by the resin particles on
the surface of the carrier is obtained according to the following
Expression.
Si--O/{(Si 2p)+(C 1s)+(O 1s)+(N 1S)+(Mn 2p)+(Fe 2)+(Ti 2p)+(Sr
3d)+(Mg 2s)+(F 1s)}.times.100 Expression:
[0331] Measurement of Total Energy Amount
[0332] 92 parts of the carrier B1 and 8 parts of the externally
added toner are put into a V blender, stirred for 20 minutes, and
mixed with each other. After this, by classifying the mixture by
using a sieve having an aperture of 212 .mu.m, a developer is
prepared.
[0333] After keeping this developer for 17 hours under an
environment in which the temperature is 25.degree. C. and humidity
is 25% RH, the total energy amount is measured according to the
above-described operations and conditions by using a powder
rheometer (FT4 manufactured by Freeman Technology).
[0334] Carrier B2
[0335] Carrier B2 is prepared in a similar manner to the carrier
B1, except that the amount of oil treated silicone particles is
changed to 0.07 parts.
[0336] Carrier B3
[0337] Carrier B3 is prepared in a similar manner to the carrier
B1, except that the amount of oil treated silicone particles is
changed to 0.008 parts.
[0338] Carrier B4
[0339] Carrier B4 is prepared in a similar manner to the carrier
B1, except that the volume average particle diameter of ferrite
particles is changed to 35 .mu.m.
Example 1
[0340] 92 parts of the carrier A1 and 8 parts of the externally
added toner are put into a V blender, stirred for 20 minutes, and
mixed with each other. After this, by classifying the mixture by
using a sieve having an aperture of 212 .mu.m, a developer is
prepared. A trickle developing type image forming apparatus
(DOCUPRINT C3200A manufactured by Fuji Xerox Co., Ltd.) is
prepared, and the above-described developer is put into the
developing device. In addition, the carrier B1 and the externally
added toner are put into the replenishment carrier accommodation
chamber and the replenishment toner accommodation chamber,
respectively.
[0341] Under an environment in which the temperature is 15.degree.
C. and humidity is 10%, an image having a toner applied amount of
4.2 g/m.sup.2 and an area of 0.06 m.sup.2 is formed on 30,000
sheets of paper (P paper sheet manufactured by Fuji Xerox Co.,
Ltd.). By monitoring the weight of the developing device before and
after the image forming, a total weight ratio of the developer
which is accommodated in the developing device is obtained.
[0342] In addition, the 30,000th image is observed with the naked
eye, and the auger mark is evaluated according to the following
standard. A and B are levels that practical use is possible without
a problem.
[0343] Evaluation Standard
[0344] A: White stripes are not recognized.
[0345] B: White stripes are slightly recognized.
[0346] C: White stripes are recognized.
[0347] D: White stripes are apparently recognized.
Examples 2 to 4, Comparative Examples 1 to 12
[0348] An image is formed and evaluated in a similar manner to
Example 1, except that combination of carriers is changed as
indicated in Table 2.
[0349] Configurations and physical properties of each carrier are
illustrated in Table 1, and configurations and evaluation results
of each Example and each Comparative example are illustrated in
Table 2.
TABLE-US-00001 TABLE 1 Configuration of carrier Oil Volume average
Weight ratio Coverage by Volume treating particle of resin resin
particles average Total Type of Resin of resin diameter of
particles in on surface of particle energy carrier particles
particles resin particles carrier carrier diameter amount Carrier
A1 Silicone No 5 .mu.m 0.1% Not analyzed 45 .mu.m 190 mJ rubber
Carrier A2 Silicone No 5 .mu.m 0.01% Not analyzed 45 .mu.m 170 mJ
rubber Carrier A3 Absent -- -- -- Not analyzed 45 .mu.m 150 mJ
Carrier A4 Silicone No 5 .mu.m 0.1% Not analyzed 35 .mu.m 250 mJ
rubber Carrier B1 Silicone Yes 5 .mu.m 0.12% 1% 45 .mu.m 240 mJ
rubber Carrier B2 Silicone Yes 5 .mu.m 0.07% 0.5% 45 .mu.m 220 mJ
rubber Carrier B3 Silicone Yes 5 .mu.m 0.008% 0.1% 45 .mu.m 180 mJ
rubber Carrier B4 Silicone Yes 5 .mu.m 0.12% 1% 35 .mu.m 300 mJ
rubber
TABLE-US-00002 TABLE 2 Total weight ratio of developer Type of
Carrier (after/before Auger Initial Replenish image forming) mark
Example 1 Carrier A1 Carrier B1 0.95 A Example 2 Carrier A2 Carrier
B1 0.70 B Comparative Carrier A3 Carrier B1 0.54 D example 1
Comparative Carrier A4 Carrier B1 1.50 C example 2 Example 3
Carrier A1 Carrier B2 0.95 A Example 4 Carrier A2 Carrier B2 0.65 B
Comparative Carrier A3 Carrier B2 0.49 D example 3 Comparative
Carrier A4 Carrier B2 1.45 C example 4 Comparative Carrier A1
Carrier B3 0.50 D example 5 Comparative Carrier A2 Carrier B3 0.45
D example 6 Comparative Carrier A3 Carrier B3 0.42 D example 7
Comparative Carrier A4 Carrier B3 0.52 D example 8 Comparative
Carrier A1 Carrier B4 1.54 C example 9 Comparative Carrier A2
Carrier B4 1.45 C example 10 Comparative Carrier A3 Carrier B4 1.46
C example 11 Comparative Carrier A4 Carrier B4 1.60 C example
12
[0350] The foregoing description of the exemplary embodiments of
the present invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed.
Obviously, many modifications and variations will be apparent to
practitioners skilled in the art. The embodiments were chosen and
described in order to best explain the principles of the invention
and its practical applications, thereby enabling others skilled in
the art to understand the invention for various embodiments and
with the various modifications as are suited to the particular use
contemplated. It is intended that the scope of the invention be
defined by the following claims and their equivalents.
* * * * *